Telephone conferencing systems enable telephone calls in which three or more people are connected and can participate in the same conversation. Telephone conferencing systems are a useful way of allowing a group of people to discuss a subject in an interactive manner, without the requirement for the people to be in the same physical location.
Telephone conferencing using the traditional public switched telephone network (“PSTN”) is achieved by each participant in the conference dialing a pre-determined telephone number that connects the participant to a conference server (also called a conference bridge). The conference server answers the telephone calls from the multiple participants to the conference, and performs the function of mixing the voice signals from each participant together and distributing the mixed signals to all of the participants. In this way, each participant is able to hear what every other participant in the conference is saying.
In addition to using the traditional PSTN system, telephone conferencing can also be achieved using Internet telephony systems. Internet telecommunications systems allow the user of a device, such as a personal computer, to make telephone calls across a computer network such as the Internet. These systems are beneficial to the user as they are often of significantly lower cost than traditional telephony networks, such as fixed line or mobile networks. This may particularly be the case for long distance calls. These systems may utilise voice over internet protocol (“VoIP”) over an existing network (e.g. the Internet) to provide these services, although alternative protocols can also be used. To use a Internet telephony service, the user must install and execute client software on their device. The client software provides the VoIP connections as well as other functions such as registration and authentication. A telephone call may be made using VoIP in accordance with methods known in the art, such as disclosed in WO 2005/009019.
Telephone conferencing using VoIP is performed in a similar manner to telephone conferencing using the PSTN. However, rather than using the PSTN to connect to the conference server, the terminals of the user connect to a conference server using the Internet. The VoIP conference server performs the decoding of VoIP audio streams from each of the participants in the conference, mixes the audio streams from the participants, encodes the mixed audio streams to VoIP, and distributes the mixed audio streams to all the participants via the Internet.
The use of peer-to-peer technology (and its associated low cost) and the ubiquitous nature of the Internet enables large numbers of users to come together from all over the world to discuss various subjects. However, the presence of a large number of participants in a telephone conference can give rise to significant problems. When the number of participants in a telephone conference are small, then a single conference server may be capable of handling all the connections from the participants. However, as the number of participants increases, the load on the conference server also increases. In particular, the CPU load increase as the number of participants increases. Therefore, for a conference server to support a large number of users, it must have a large amount of processing power. When the load on the conference server reaches a certain limit, then the conferencing server must either refuse the addition of more participants or risk becoming unstable due to overloading.
In addition to the above-mentioned issues regarding the handling of large numbers of users at the conference server, there are also other issues regarding the control and management of large conferences to consider. From a usability perspective, it becomes very difficult to manage a discussion over a telephone conference when the number of participants is large. This is because several people will tend to try and talk at any instance in time, leading to overlapping voices and confusion, which interrupts the flow of the discussion. This can particularly be the case if there is any delay present on the voice signals, as this can cause people to repeatedly talk over each other, leading to a stop-start type of conversation. In addition, there is also a problem with identifying a particular participant who is talking from a large group of people. When a person begins talking in a telephone conference containing a large group of people, the identity of the person talking may not be clear. This may require the person to be interrupted in order to establish their identity, and may in turn lead to the problems above of several people talking at once. These problems limit the usefulness of telephone conferences for discussions between large groups of people.